DESCRIPTION The long term goal of the parent grant for this application is to identify, isolate, and characterize genes associated with susceptibility or refractoriness of mosquito species to Plasmodium parasites and to use this information to develop a malaria disease control strategy based on genetic disruption of mosquito vector competence. The specific aims of this project are: 1. to isolate genes that influence P. gallinaceum susceptibility from Ae. aegypti, 2. to knock out the identified genes to determine if they indeed control susceptibility, 3. to determine if parasite exposure selects for specific populations of alleles, and 4. to construct a RFLP linkage map for the mosquito Anopheles gambiae, the host for the human malaria. This FIRCA application describes experiments that directly extend results obtained in the parent project to study the population dynamics of Ae. aegypti particularly as it relates to mosquito control measures. Ae. aegypti is the host for Dengue virus as well as yellow fever virus. Dengue virus is a prevalent infection in tropical areas and the only measures against this disease are vector elimination by insecticides, an approach that has not been entirely successful. This project will utilize the RFLP map generated by the parent project to explore the genetic diversity of these mosquitoes and the population dynamics of mosquitoes as a result of insecticide usage. The goal is to understand the mechanism for mosquito survival after insecticide application in order to develop more effective control strategies. Specifically four sites in Trinidad and Tobago have been selected for analysis. Eggs will be collected from the four sites before, 2-3 weeks after insecticide application, and 3-4 months after insecticide application. DNA from resulting individual mosquitoes will be characterized by Southern blots using 10-12 RFLP markers developed by the parent grant. RFLP genotype frequencies at individual study sites will be evaluated with respect to Hardy-Weinberg expectations. To assess genetic divergence between populations, the genetic distance matrices will be calculated using Nei's unbiased genetic distance estimator. The data will be analyzed to determine levels of genetic similarity among populations from different sample sites and to assess the population dynamics after insecticide treatment. Questions to be asked are: 1. is survival after insecticides due to the selection of resistant populations or is survival a function of non contact with insecticides, and 2. is the increase in population after insecticide due to expansion of a resistant population or due to immigration from other sites.